Drug interactions
Fosphenytoin + Tolazamide
Severity: Minor
Fosphenytoin and Tolazamide: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Tolazamide may displace phenytoin, the active product of fosphenytoin, from plasma proteins and transiently raise the free fraction. Phenytoin can also impair insulin release and raise glucose, making diabetes control less predictable.
What this interaction means in plain words
Fosphenytoin and Tolazamide have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosphenytoin belongs to Central Nervous System; Tolazamide belongs to Endocrine.
Why it happens
Competition for plasma protein binding sites, with possible pharmacodynamic opposition from phenytoin on insulin secretion.
What to do
Monitor free phenytoin levels and blood glucose when the combination is started or changed. Adjust doses based on response.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Tolazamide
- Disopyramide + Tolazamide Major
- Insulin degludec-liraglutide + Tolazamide Major
- Aceclofenac + Tolazamide Moderate
- Acemetacin + Tolazamide Moderate
- Acetylsalicylic acid + Tolazamide Moderate
- Albiglutide + Tolazamide Moderate
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Tolazamide?
MediHelp rates the interaction as minor. Fosphenytoin and Tolazamide have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Tolazamide may displace phenytoin, the active product of fosphenytoin, from plasma proteins and transiently raise the free fraction. Phenytoin can also impair insulin release and raise glucose, making diabetes control less predictable.
How serious is the interaction between Fosphenytoin and Tolazamide?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor free phenytoin levels and blood glucose when the combination is started or changed. Adjust doses based on response.
What other medicines interact with Tolazamide?
MediHelp also lists interactions of Tolazamide with, for example, Disopyramide, Insulin degludec-liraglutide, Aceclofenac. The full list is on the Tolazamide page.
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